Electric floor heater



April21 1925. 1,534,221

A. J. KERCHER ET AL ELECTRIC FLOOR HEATER kFiled March l0, 1924 Patented Apr. 2l, 1925.

UNETED STATES PATENT QEFFECE.

ARTHUR J'. KERCHER, 0F BERKELEY, AND WILEIAM WESLEY HICKS, 0F SAN FRANCISCO, CALIFORNIA.

ELECTRIC FLOOR HEATER.

Application led March 10, 1924. Serial Il'o. 698,090.

To all 'whom z't may concern;

Be it known that we, ARTHUR J. K ERCHER and WILLIAM WESLEY HICKS, citizens of the United States, and residents, respectively,

of the city of Berkeley, in the county of Alameda, State of California, and of the' city and county of San Francisco, State of California, have invented a new and useful ElectricfFloor Heater, of which the following is a specification.

This invention relates to a device for heating a room or other space, by the aid of electrical energy. More particularly the invention relates toa heater that is adapted to be installed in a recess in the oor of the room, and having an opening covered by a grille.

It is one of the objects of our invention to improve in general this type of electric floor heater. d

In heaters of this type, the grillev is iush. with thefloor surface, and must be kept unobstructed so as to permit the air heated by the heater to rise Afreely into the room.

currents, tending to equalize the room temperature, and which are therefore so desirable. If by chance it should happen that the rise of air is impeded, as for example, by covering up the grille with a rug or an article of furniture, temperatures of dangerous value may be easily attained near the heater. It is one of the objects of our invention to prevent the occurrence of such high temperatures under all circumstances, and thereby ensure against destructive fires.

Our invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description, where we shall outline in full that form of the invention which we have selected for illustration in the drawings accompanying and forming part of this specification. Although we have shown in the drawings but one embodiment of our invention, we do not desire to be limited thereto, since the invention as defined in tllie claims may be embodied. in other forms a so.

Referring to the drawings:

Figure 1 is a sectional view of a heater as installed, embodying our invention, the current carrying wires being omitted for the sake of clearness;

Fig. 2 is a top plan view of the heater This rise of heated air produces convection,

shown in Fig. 1, with a portion of the apertured cover or grille removed,the better to expose the construction; and

Fig. 3 is a fragmentary sectional view, taken along plane 3-3 of l? ig. 2.

The surface of the Hoor is indicated at ll; the heater is supported in a box-like casing 12, sunk into the Hoor 11 and held thereto, as by the aid of the flange 13 extending around the open edge of casing 12. This casing is preferably made from sheet metal. The bottomll is shown in this instance as formed of a separate piece of metal, held to the sides by the aid of theturned down flange 15 extending around the bottomplate 14. `All a ertured cover 16 forms a grille through w ich air may pass to and from one or' more electric heating units 17 supported near the bottom of the casing 12.

In the present instance we show four heating units, but of course as many may be used as desired. The wires carrying the heating currents are shown only diagrammatically in the figures, since in the present case our invention is not concerned with the details of these heaters. rlhey will be described in somewhat general terms. Each unit consists of a vertically arranged hollow column of refractory material, such as clay. These columns each have one or more grooves 18 which wind around, in helical fashion, on the periphery of the column, and serve to support the heating conductors. These conductors are usually in the form of long helical coils of wire, having adiameter just large enough to permit ready insertion 1n the grooves '18.. The terminals of the coils may be made to pass through the small holes 19, whereby the coils themselves may also be anchored at their ends.

The units 17 are supported in this instance from the bottom of the casing 12, and in'vertical positions, by the aid of the U- shaped straps 20, two for each element, which cooperate with thejlanges 21 of the elements 17. The straps 20 are purposely arranged to provide an open space between the bottom of the elements 17 andthe bottom 14 of the casing. In this way, air may freely enter at the bottom of the vertical apertures 22 and rise through the heating elements and the register 16 into the room.

For still further' ensuring .proper air ingress -at the base of the heater elements 17,

.we provide spacers 33 between the top of the straps 20 and the bottom o f the flanges 2l The rising of heated air in and around the 'elements 17 causes an air circulation, involving the reciprocal function of passing cool air downward to the heaters. Without special precautions, the rising warm air and falling cool air would interfere with euch other, and cause retarded circulation. In order to overcome this effect, we provide separate passageways for the cool air, preferably near the edge of the casing 12, by the aid of a rectangular hollow Hue member 23. This member 23 forms an annular space 24 all around the casing 12. It is supported from the inner surfacel of the casing 12 by the aid of a plurality of short straps 25. The member 23 furthermore does not extend clear to the bottom of the casing 12, but is spaced therefrom to permit communication between the annular space 24 and the space adjacent the heaters 17. T he cool air can then be taken in through this space 24, and hot air can be discharged centrally of the entire heater.

It is important to keep the cool and warm air in their movement as well segregated as possible. In order to further this object, we preferably provide a supplementary insulation space 26, located between the space 24 and the heater interior. This space 26l may readily be formed by the aid of a still smaller rectangular hollow member 27, nested inside of the flue member 23. This 'l member 27 is supported from the inner wall of the member 23 by the aid of the short straps 28, and likewise has an open bottom resting above the bottom of casing 12. The nested hollow rectangular members 12, 23 and 27 thus form a plurality of annularlike spaces 24 and 26, which surround the interior space defined by the smallest rectangular member 27. The space 26 is substantially a dead airspace, in which little if any movement of air is produced. The circulation of the airis about as indicated by the short arrows. The cool air is supplied near the base of the elements 17; in rising therefrom it is gradually heated and finally enters into the room through the openings in grille 16.

It may very readily happen that a rug or an article of furniture placed over the register 16 soimpedes the air circulation that dangerous temperatures would result near the heater. In that case, the normally cool insulation space 26 receives a considerable portion of heat, and temperature within its rises rapidly. This is due to the fact that in normal operation this space receives very little heat, but when circulation is impeded, the warm air fills this spacefas well as all of the other spaces in the heater. In cada: to permit this circulation, both rectangular flue members 23 and 27 do not quite extend up to the grille 16. We make use of this large variation in temperature to actuate a safety device, such as a thermostatswitch 29, which is supported in the member 23 and is subjected to the temperature of space 26. Since the details of the thermostat are of no consequence as regards the present invention, it will be described only in general terms. We prefer to use a pressure cell type of thermostat, having a closed chamber 30 with a buckled diaphragm, and containing a readily volatilizable liquid. When a temperature is reached that raises the vapor-pressure in the cell 30 sufficiently to move its diaphragm, certain contacts are operated by this movement to cause de-energization of the elements 17. In order to permit ready access to the contacts as well as to the other parts of the thermostat, an aperture 31 is provided in the outer casing 12, registering with the thermostat, and normally closed by a cover 32.

The sudden rise in temperature in space 26 due to impeded circulation of the air serves as the operating cause for shutting down the heater. In this way conditions that would very likely prove dangerous are corrected or nullied at the outset.

Ve claim:

1. In an electric heater, a casing, an apertured cover for the casing, and means forming with the interior walls of the casing a passageway extending around the element and communicating with the interior near its bottom, said passageway also communieating with the interior near its top, through a path distinct from the apertures in the cover.

2. In an electric heater, a casing having vertical sides, a.- heating element having a vertical aperture therethrough spaced from the bottom of the casing, and a vertical walled member extending around the element and spaced both from the top and the bottom of the casing, said member forming a passageway with the interior vertical walls of the casing, whereby cool air may be conducted into the casing.

3. In an electric heater, a casing, an apertured cover for the casing, a heating element supported in said casing and spaced from the bottom thereof, means forming an annular-like passageway extending around the element for conducting cool air to the interior of the casing, and means forming an insulating air space between the heating element and the passageway. 4. In an electric heater, a casing, an apertured cover for the casing, means forming with the interior walls of the casing a passageway extending around the element and communicating with the interior near its bottom, and means forming an insulatin air space between the heating element an the passageway, said air space and passageiso way communicating both at the top and the bottom with each .other and the interior, the communication at the top boing through a. path distinct from the apertures in the cover.

5. In an electric ioor heater, a casing arranged to be placed below the surface of a oor, and having vertical sides, a heating element having a vertical aperture therethrough spaced from the bottom of the casing, and a plurality of vertical `walled members extending around the element, and spaced from the bottom of the casing, said members forming, with the interior of the casing, a plurality of annular-like passageways near the edges of the casing.

6. In an electric floor heater, a casing arranged to be disposed below the floor surface and havingr an apertured cover to permit heated air to rise therefrom, an electric heating element supported in said casing, and thermal responsive means arranged to operate upon the stoppage of free emission of air from the casing, for controlling the element.

7.. In an electric floor heater, a casing arranged to be disposed below the ioor surface, and having an apertured cover to permit heated air to rise therefrom, an electric heating element supported in said casing, and a temperature responsive device in said heater, for controlling the heating element.

8. In an electric iioor heater, a casing arranged to be disposed below the floor surface, and having an apertured cover to permit heated air to rise therefrom, an electric heating element supported in said casing, means forming a plurality of annular-like passageways around the element, said passageways being formed with vertical walls-within the casing, and spaced from the interior walls'` thereof, said passageways communicating with the bottom of the casing, and also with the top of the casing through a path distinct from the apertures in the cover, and a thermostat for controlling the element subjected to the temperature of one of the passageways which is between the element and the outer passageway.

9. In an electric floor heater, a casing arranged to be disposed below the floor surface, and having an apertured cover to permit heated air to rise therefrom, said casing having vertical walls, an electric heating element disposed near the bottom of said casing, means forming with the interior walls of the casing, a pair of vertical walled passageways surrounding the element, and opening to the bottom of the casing, the outer of said passageways serving to conduct cool air to the heater, and the inner as an insulation space between the element and the other passageway, both passageways also communicating with the interior of the casingnear its top, through a path distinct from the apertures in the casing and a thermostat for controlling the element, respon-v sive to the temperature in said insulation' space.

ARTHUR J. KERCHER. WILLIAM WESLEY HICKS. 

